Tobiiro Shadow

From Emily's Random Shoujo Manga Page:
It all begins long ago in the past. In a place near an ancient wall. The wall looks more like a cliff, really. Anyway, two cute children grew up together. Sumire is a gentle girl, and Yasuhira is a bossy boy, but he loves Sumire. When Yasuhira proposed marriage to Sumire, it was more like the confirmation of a long-held assumption that they would eventually wed. But they did lot live happily ever after. We see a bloodied sword, and someone crying…

Flash forward to modern times. These days, a school has been built near the ancient wall. It is such a tall, imposing wall/cliff thing, that naturally the students have made up ghost stories about it. Some of the girls are determined to go to the wall, where they believe they can see some real ghosts. A classmate, Sumire, is unwillingly dragged along. Sumire tries to get out of going, but her friends insist. When they get to the wall, Sumire feels an unusual wind, and then is confronted with a startling sight — a boy crying. He is just standing there, tears pouring down his cheeks. Before she can say anything, her friends call her away. The boy looks startled to see her. Sumire realizes he looks familiar… is that her classmate Katsuragi-kun?